Dyeing polypropylene



United States Patent 8 Claims. (Cl. 8-4) The invention relates to a method for the dyeing with disperse dyes of shaped articles of polypropylene 1n the presence of an aromatic compound as carrier.

The use of certain aromatic compounds, such as benzene, xylenes, chlorobenzenes, and ethyl benzenes, as carriers for the dyeing of polyolefines has already been proposed. This proposal, however, only gives satisfactory results when dyeing articles of polyethylene. When applied to articles of polypropylene, this process gives little fastness or resistance'towaslu'ng or rubbing because, on account of its special crystalline structure, polypropylene is less accessible for dyestufis than is polyethylene. When articles of polypropylene are dyed by the above-mentioned known process, the dyestufi merely deposits on the surface of the material so that it is readily removed by washing'or rubbing.

Surprisingly, it has now been found that shaped articles of polypropylene may be dyed in such fashion that they have a high fastness to washing and rubbing by carrying out a process of the above-mentioned broadly known type in such a way that, as a carrier, use is made of an alkyl phenol, the alkyl group of which contains at least 6 carbon atoms.

By using the method according tothe present invention, it becomes possible to obtain well dyed articles of polypropylene, for instance textile products of polypropylene which are colored throughout, as may be readily demonstrated by microscopic examination of the cross-section of a polypropylene fibre dyed by this process.

The method according to the present invention can be used for dyeing the most widely varying shaped articles of polypropylene, such as for instance, films or articles obtained by the injection-molding process. The invention is of particular importance for dyeing textile products and textile starting materials made of polypropylene.

It is possible to dye the polypropylene granules from which the threads are spun or to dye the threads themselves either in the stretched or in the unstretched state. Also fibres, yarns, Woven or knitted fabrics, or other textile products, consisting entirely or partly of polypropylene, may be dyed by the process according to the present invention.

The polypropylene may contain other substances, such as pigments and stabilizing compounds. The articles formed also may consist of mixtures of said polypropylene polymers or of said polypropylene polymers with other polymers.

The disperse dyes used in the process according to the present invention are per se known compounds which are practically insoluble in water. They are used in industry on a large scale, e.g., for dyeing textile material of cellulose acetate and polyethylene terephthalate.

The polypropylene material to be dyed is preferably steeped in a heated aqueous dispersionof the given dye. This dispersion will preferably always contain a dispersing agent, such as an ethoxylated alkyl phenol, a sulphated fatty alcohol, or a sulphonated mineral oil. Polypropylene textile materials may also be steeped in a concenlice trated aqueous suspension of the dye and heated for some time at a temperature of, say, 140 C.

It should be noted that the eEnoxylated-alkyl phenols used as dispersing agents do not at all show an elfect on the dyeing of polypropylene to the extent shown by the alkyl phenols used according to the present invention.

The process according to the present invention may be carried out in any of the known ways usin disperse dyes, care being taken, however, that the method is carried out in the presence of an alkyl phenol, the alkyl group of which contains at least 6 carbon atoms. 7

The alkyl phenol employed according to the present invention is preferably used in such manner that it is added to the dye liquor, as is usual when employing carriers -together with the disperse dyes. But it is also possible for the. polypropylene textile products first to be treated with the alkyl phenol and then to be dyed. The latter method, however, otters no advantages over vthe method where the alkyl phenol is added directly to atoms. This alkyl group may be in ortho, meta, or para The position relative to the hydroxyl group or groups. carbon atoms in the alkyl group may form a straight or a branched chain. Use will be made, generally of mixtures of isomeric alkyl phenols for practical reasons, because ordinarily such mixtures are obtained upon preparation of these compounds on an industrial scale. Indeed, more often than not such mixtures not only contain various isomers but also small amounts of closely related homologous compounds. Said alkyl phenols may also have one or more additional alkyl substituents attached to the aromatic ring, such as methyl, ethyl, and higher alkyl groups. It is also possible to make use of a mixture of alkyl phenols the alkyl groups of which differ substantially in carbon atom content.

According to the present invention, it has been found that the p-alkyl phenols the alkyl groups of which contain at least 6 and up to 15 carbon atoms, and preferably from 8 to 12 carbon atoms, yield the most favorable results because they strongly further the penetration by the disperse dyes, even when employed in relatively small quantities.

limits. In the case of alkyl phenols where the alkyl groups contain from 8 to 12 atoms, an amount of 0.5 part by weight to parts by weight of the dye liquor is generally amply sufiicient.

When use is made of an amount of 0.1 part by weight to 100 parts by Weight. of dye liquor, however, the effect on the penetration is still clearly visible. In the case of alkyl phenols where the alkyl groups contain 6 to 7 or more than 12 carbon atoms, for example up to 15 carbon atoms, use will be made generally of somewhat larger amounts, for instance, of 0.7% by weight. Generally speaking, there are no advantages in using considerably more than 1.0% by weight of the alkyl phenol, based on the dye liquor, and therefore from 0.1 to 1.0% by weight, based on the dye liquor, may be regarded as the optimum range.

According to the present invention, various disperse dyes or mixtures thereof, make it possible to dye shaped articles of polypropylene in the most Widely varying colors.

The present invention comprises, in addition to the ene dyed by this method.

methods described herein,

,It should be noted in passing that a method has been suggested according to which polypropylene is dyed by bringing it into contact, at a relatively high temperature, with a mixture ofdyestuff soluble in fat and a chlorinated aromatic cdmpound, such as dichloronaphthalene. This shaped articles of 'polypropylmethod, however, has the disadvantage that the dyeing l process must be carried out in a very special manner which does not permit the" application of the widely employed industrial method using an aqueous dyebath. An-

other drawback to that method consists in that shaped articles which are dyed may undergo undesirable dimensional changes as a result or" the swellingefiec'ts on polypropylene of the compounds used.

present invention; the following examples :of typical procedure are set forth, it being understood however that this description is'here presented by way of illustration only and not as limiting the scope of the invention.

Example I (a) A sample of 100 parts by weightof tubular hosiery of a 75 -denier polypropylene yarnconsisting of 24 filaments is'introduced into a dyeliquor present in an autoclave, after which the temperature of the dye liquor is raisedto 130 C. The dye liquor consists of 8,000'parts by weight of water, 9 parts by weight of a red disperse dyestuff (Rouge estrophilelumiere RBL Extra, made by Messrs. Francolor, Colour Index No. 11040), 80 parts by weight of the sodium salt of sulphated stearyl alcohol as dispersing agent,-and 40 parts by weight of para-nonyl phenol. The para-nonyl phenol is brought into a finely divided state by first dissolving it in a'small amount of sodium hydroxide, adding the resulting solution to the dye liquor, and then neutralizing this dye liquor with acetic acid. 1

After-2 hours, the sample is taken out of the bath and is found to show a highly red color.

It is soaped by keeping it immersed for 15 minutes in a boiling 5% aqueous solution of sodium stearate. The

sample then shows a. highly red color and upon microscopic examination of the fibre cross-section, the single" filaments appear to be dyed right through to the core.

(b) On repeating the foregoing procedure in the absence of para-nonyl phenol in the dye bath, the sample shows only a faint red color upon removal from the dyebath, and after soaping it is practically colorless.

(c) The foregoing procedure is repeated a number of times, para-nonyl phenol being replaced successively by carriers used conventionally in the dyeing of polyester and of polyethylene fibre material, namely; benzoic. acid, dichlorobenzene, ortho-phenylphenol, diphenyl and orthochlorotoluene. Upon removal from the dyebath the samples indeed show a highly red color, but upon soap- 7 ing in the above-indicated.manner they lose this color" In order to indicate still more fully the nature of the completely or almost completely.

(d) Theforegoing procedure is repeated a few more times, .'and in such manner that; parts by Weight of a condensation product of nonyl phenol and ethylene oxide are used as-a dispersing agent, and that instead of nonyl phenol as carrier useis made of 2,2-di(4 -hydroxyphenyl)- propane, ortho-cresol, para-cresoL' para-*ethylphenol,

para-propyl phenol, and para-butyl phenol, respectively. b

Upon soaping, the samples almost or completely lose the color initially assumed. I

Example 11 In the manner described in Example In above, an identi it cal sample isdyed, use being made now of a yellow dis:

perse dyestulf (Cibacetgelb 4 G made by Ciba, Colour Index No. 12790), para-dodecylphenol being used in an equal amount instead of nonyl phenol as the carrier. 7 Upon soaping in the manner described above, the sample still shows a highly yellow color.' Upon micro-I scopic examination of the cross-section of the single filaments of polypropylene, the dye appears to have penetrated right through to the core.

Examplelll I In the manner described in Example Ia above, another identical sample is dyed, use being made now of a blue disperse dyestuff (Palanilblau RD'made by "Messrs Badische Anilin -und Sodafabrik, Colour Index No; 61500), octyl phenol being used in an amount equal to and instead of nonyl-phenol as carrier.

Upon soaping as above, the sample still shows a highly blue color. Example IV I In the manner described in Example Iafabove, another '7 of C. consisting of 10,000 parts by weight of water, I

3 parts by weight of a red disperse dyestutf "(Rouge estrophile lumiere' RBL Extra, Colour Index .No. 11,040), 30 parts by weight of sulphonated ricinus oil (castor oil) as dispersing agent, and 50 parts by weight of pma-nonyl phenol.

The sample is "subsequently dried and heated for 1 hour at C. Upon soaping in the manner indicated above in Example I, the sample still showsa highly red color,-

Upon microscopic examination it is found thatthe'iila ments aredyed right through to the core; a

While specific examples of prefer-red methods embodying the present invention have been described above, it

will be apparent that many changes and modifications .may be made in'the details thereof without departing from the spirit of the invention. It will therefore .be understood that the examples cited andthe particular method of procedure set forth above are intended to be illustrative only, and are not intended to limitthe scope of the invention.

What is claimed is:

1. In a method for dyeing, shaped articles of poly: propylene with disperse dyes in the presence of an aromatic compound as carrier, the steps of employing as carrier an alkyl phenol thealkyl group of which contains.

from 6 to 15 carbon atoms. 7

2. A method according to claiml, wherein the alkyl phenol-is apara-alkyl phenol the alkyl group of which.

contains from 8 to 12 carbon atoms. p

3. A method according to claim 2, wherein the alkyl phenol is used in an amount of 0.1 to 1.0%- by weight,

based on the amount of dye liquor.

4. Shaped articles of polypropylene dyed according to the process of claim 1.

5. A method for imparting a fast color to a shaped textile material made of polypropylene, comprising sub-: jecting said shaped textile material to treatment in a hot. aqueous dyebath containing at least one-disperse dye and in an aromatic compound as carrier, said carrier being an alkyl phenol the alkyl group of which contains from 6 to 15 carbon atoms, and removing dyed shaped textile material of polypropylene from the hot dyehath, whereby the desired color is imparted throughout the shaped textile material of polypropylene such that the color is not removed after immersion of the shaped textile material for 15 minutes in a boiling 5% aqueous solution of sodium stearate.

6. A method according to claim 5, wherein the alkyl phenol is a para-alkyl phenol the alkyl group of which contains from 8 to 12 carbon atoms.

7. A method according to claim 6, wherein the alkyl phenol is used in an amount of 0.1 to 1.0% by weight, based on the amount of dye liquor.

8. Shaped articles of polypropylene dyed according to the process of claim 5 References Cited by the Examiner UNITED STATES PATENTS 2,926,987 3/60 Freyermuth et a1. 2,984,634 5/61 Caldwell et a1. 2,989,358 6/61 Jurgeleit 8-41 FOREIGN PATENTS 445,345 3/36 Great Britain. 809,495 2/59 Great Britain.

OTHER REFERENCES Schwartz et al.: Surface Active Agents and Detergents, vol. II, 1958, pp. 190, 191.

NORMAN G. TORCHIN, Primary Examiner.

ABRAHAM H. WINKELSTEIN, Examiner. 

1. IN A METHOD FOR DYEING SHAPED ARTICLES OF POLYPROPYLENE WITH DISPERSE DYES IN THE PRESENCE OF AN AROMATIC COMPOUND AS CARRIER, THE STEPS OF EMPLYING AS CARRIER AN ALKYL PHENOL THE ALKYL GROUP OF WHICH CONTAINS FROM 6 TO 15 CARBON ATOMS. 